虚拟语气
虚拟语气表示与客观事实相反的假设，由if虚拟条件从句和主句构成。
一、虚拟语气的基本内容
根据虚拟与其这种与事实相反的假设所对应的时间不同，虚拟语气的if虚拟条件从句与主句的谓语动词分别有三类构成形式：
假设类型If虚拟条件从句
主句与现在事实相反 Did/were Would/should do 与过去事实相反 Had done Would/should have done 与将来事实可能相反 Were to do/did/should do Would/should do
例：1、I wouldn't talk that way if I were Peter.
2、If the whole operation had not been planned before hand, a great deal of time and money
would have been lost
3、Jean doesn't want to work right away because she thinks that if she were to get a job she probably wouldn’t be able to see her friends very often.
4、I would ask George to lend us the money if I knew him.
5、Do you think there would be less conflict (战斗、斗争) in the world if all people spoke the same language.
6、If Bob had come with us, he would have had a good time.
二、if的省略形式(又称虚拟语气的倒装结构)
在if虚拟条件从句中，如果谓语部分包含were，should，had等词，则可以把这些词放到主语前，省略if，构成虚拟语气的倒装结构。
三、主句与从句时间不一致时虚拟语气的构成
当虚拟语气的if虚拟条件从句和主句的动作发生的时间不一致时，要根据各自表示的时间采用对应的虚拟语气的构成形式。
例：1、If I had attended the meeting yesterday, I would know what happened now.
2、If you had taken our advice at that time, you would not be in trouble now.
四、主观倾向性动词引导的虚拟语气的构成
在英语中存在一些动词，表示建议、命令、要求等主观的倾向，由这些动词引导的that宾语从句中，从句的谓语动词要用should+动词原形，should可以省略。这类常见的主观倾向性动词有“一坚持、二命令、三建议、五要求”，分别是：
一坚持：insist 二命令：order、command 三建议：suggest、advise(n advice)、propose(提议、建议) 五要求：ask、demand、require、request、desire
例：1、The doctor advised that Mr. Malan have an operation right away so as to save his life.
2、His mother insisted that he put on the coat when going out. 同时，如果在题干中出现上面这些主观倾向性动词的名词和形容词形式，题干中从句部分的谓语动词也要用should+动词原形，should可以省略。考试中常见的词汇有：order，command，suggestion，advice，proposal，demand，request，desire，advisable，desirable.
五、wish that和if only引导的虚拟语气的构成
Wish that引导的宾语从句和if only引起的感叹句都用虚拟语气来表示一种没有实现或无法实现的愿望，其中wish that句型往往翻译为：多么希望?;if only表示的愿望较wish that更强烈，常翻译为但愿;要是?就好了。两者的用法基本相同。两者的用法是：1、当表示与现在的事实相反的一种愿望时，wish that引导的宾语从句和if only引起的感叹句中谓语动词采用的形式是：did/were;
2、当表示与过去的事实相反的一种愿望时，wish that引导的宾语从句和if only引起的感叹句中谓语动词采用的形式是：had done;
3、当表示未来一时很难实现的一种愿望时，wish that引导的宾语从句和if only引起的感叹句中谓语动词采用的形式是：would do.
六、would rather引导的虚拟语气的构成
Would rather的意思是“宁愿、宁可”其引导的宾语从句(一般省去that)通常用虚拟语气表示一种与事实相反的假设。我们可以假设A.B是两个人，通过牢记一下句式来记住其用法：
1、A would rather B did sth：表示与现在或将来事实相反的一种假设
2、A would rather B had done sth：表示与过去事实相反的一种假设
